Closed conditioned crawlspace
I’m doing a closed, conditioned crawl space for our new 2500 sq ft, single level home in western North Carolina.
My question is what material to use to seal the mating surfaces at top and bottom of the sill plate and at top and bottom of the band joist shown as Item #1 in this pdf
GC and I have discussed using strips of Bituthene or a similar product, or maybe simply going around the crawlspace perimeter with an application of caulk.
Also, re Item #15 shown on the same pdf, we need to do the following “Slope drains to daylight and include an accessible backflow valve and 1/4-inch rodent screening.”
Can anyone please recommend website links to “backflow valve and 1/4-inch rodent screening”, so I can view and maybe order these items.
Comments appreciated.
Edited 3/7/2008 8:18 am ET by RhondaRay
Edited 3/7/2008 8:20 am ET by RhondaRay
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Replies
"what material to use to seal the mating surfaces at top and bottom of the sill plate and at top and bottom of the band joist"
There is a product sold for specifically for the sil plate. I believe I've seen it at Home Depot and/or Lowes. I think it is a thin layer of some kind of styrofoam in a roll. Not sure how that would work at the band joist.
I wouldn't use caulk, I'd use polyurethane foam (Great Stuff or similar).
"backflow valve and 1/4-inch rodent screening"
The backflow valve is a standard plumbing item. Depending on the size of the drainpipe, you can probably get it at Home Depot/Lowes. Almost certainly a plumbing supply house would have it.
The rodent screening would just be hardware cloth at a hardware store, as far as I know.
Rich Beckman
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Use standard 1/4" x 6" foam sill seal for sill to foundation, and either Tremco acoustical sealant or epdm gaskets (like the BG61) for band joist edges.
http://www.conservationtechnology.com/downloads/BuildingGaskets.pdf
I have several issues with the recommendations you linked to.
There should be no need for a floor drain in a crawl space if the perimeter of the foundation is well drained. So forget the backflow preventer, but always use a critter screen on the outflow of the perimeter drain.
I also have concerns about leaving inside foam board 3" off the bottom and - more importantly - down from the top where most of the heat loss will occur. Extruded polystyrene (XPS) will not wick water, but could become a conduit for insects. So rather than leaving it low at top, install a metal flashing insect barrier above.
Solar & Super-Insulated Healthy Homes
"I also have concerns about leaving inside foam board 3" off the bottom and - more importantly - down from the top where most of the heat loss will occur. "Unfortunately, that's specified in the North Carolina Building Code.http://www.ncdoi.com/OSFM/Engineering/BCC/Documents/Minutes/040914c.pdfThanks for the advice, re EPDM gaskets from conservationtechnology.com
Rhonda, call your inspections dept to see if you really have to leave 3". If the walls are accessible, you may be able to get away with less.Definitely put in the floor drain, or some kind of crawl space drain if you are going to have a water heater with a drain pan, or an air handler with a condensate line down there.If you go with foam insulation, have the band foamed. The foundation walls can also be foamed. Where in NC are you building? Winterlude, Winterlude, my little daisy,
Winterlude by the telephone wire,
Winterlude, it's makin' me lazy,
Come on, sit by the logs in the fire.
The moonlight reflects from the window
Where the snowflakes, they cover the sand.
Come out tonight, ev'rything will be tight,
Winterlude, this dude thinks you're grand.
Here it is December and we are mere weeks away from a CO. The conditioned crawlspace has generated a ton of local interest and numerous compliments from the subs that have worked under the house.Because we installed a temporary ground cover vapor barrier early-on, and have run a dehumidifier set a 50% RH, the crawlspace remained cool and dry during the summer, and now warm and cozy during the early days of winter.The masonry contractor finished the wall perimeter with solid, 4" cap blocks and the sill plates and rim joists were installed on the foundation using gasket products from http://www.conservationtechnology.com/downloads/BuildingGaskets.pdf/, specifically BG65 and BG32. The framing carpenters were initially skeptical but, with my prodding, came to appreciate the extra effort.The GC and I have worked with the plumber, electrician and HVAC installers, making sure that all openings have been filled. Grading and exterior foundation waterproofing were attended to properly.The HVAC is designed to dump a small amount of supply air into the crawl space and we will monitor the damper opening vs. temperature and relative humidity.The final step will be to install a permanent vapor barrier per NC and local building code. We are working with the local inspector, trying to get a definitive answer re. R value of the inside foundation wall rigid insulation (e.g., Dow Thermax). Suggestions are for the 1-1/2" thickness variety.Thanks to this board for all the suggestions (since March).As always comments and suggestions are appreciated.RhondaRay
I finished my 2500 sq. ft. house just 3 year ago. Put it on a sealed crawlspace built with ICFs, foamed rim joists and a vapor barrier (Tu-Tuff) sealed to walls, etc. We also dump a bit of conditioned/heated air into it. I could not be happier. In the winter the floors are warm and the crawl space is just like another room.
I think you are going to be pleased.
I did have to cover the ICFs with sheet rock for fire protection but they did let me have foam in the rim joist area.
Look into Triple Guard from Protecto Seal. This is
a sealer with a T-shaped cross section that seals on
three surfaces at the intersection of sill with
foundation. They claim dramatically increased
airtightness.
http://www.protectowrap.com/product_specs.php
Wondering if any forum members have used Protecto products, if so, which ones?